Energy can never be __________ or __________,
it can only be ______________ from one _____ to another.
Energy can only be used when it is transferred from one form to another.
This is called ______.
When work is done some of the energy is transferred into __________ forms, while some of the energy will be transferred into _________ forms.
A light bulb is supplied with a total of 150J of electrical energy.
The bulb gives off 60J of light energy.
Calculate the percentage efficiency of the bulb using the equation:
How much energy
does a 150W light
bulb transfer in:
a) three seconds
b) one minute
A 2,500 W electric heater is switched on for 4 hours.
Calculate the energy used
in that time and the cost of using the appliance if
1 unit costs 9 pence.
A 200W TV is used for an average of 3 hours each day.
Calculate how much the TV costs to run per week.
Cost of 1 unit =
10 pence.